Detecting Patterns in MPI Communication Traces

Abstract

Since processor counts in supercomputers are increasing dramatically, efficient interprocessor communication is becoming even more important for the applications that run on them. A high level, abstract understanding of an application's communication behavior would not only simplify debugging of that communication but would also support more directed performance optimization. We explore automated identification of communication patterns to provide that high level abstraction. We introduce an algorithm to extract communication patterns from MPI traces automatically. Our algorithm first finds locally repeating sequences and then iteratively grows them into global patterns. We demonstrate our technique on three realistic codes using traces from up to 128 processors. Our results show that our approach detects the underlying communication pattern within reasonable time andmemory constraints, even for large trace sizes.